1. Technical Field
The present invention relates to a method, software and apparatus for providing an undo/redo mechanism.
2. Description of Related Art
Undo/redo mechanisms are provided in the user interface of many computer applications. They provide the capability to “undo” tasks that were performed, previously by repeatedly pressing the undo button, which causes the application to undo commands one by one in reverse succession. Hereto, a history of user actions is stored by the computer application. Most user interfaces that include an undo command also include a redo command that allows a user to redo the last command that was just undone. In this manner a user can press the undo button repeatedly until he has backed up to a suitable point, and can then use the redo button if he has backed up too far, or if he decides to redo the task just undone. Instead of using mouse clicks for the navigation through the history, it is also known to scroll through a history list and select an item there from (web browser history). Undo/redo works well for a limited amount of undo/redo actions. If the number of actions is too great, for example in case of continuous change, such as occurs in surveying, exploring, measuring, or drawing, undoing by navigating through discrete actions becomes infeasible.
It is an object of the invention to provide an improved method and apparatus, which is particularly suitable for applications with continuous changes.